Transfer object

ABSTRACT

A transfer object comprises a substrate having one or more fine concave portions formed on a surface thereof. At least one of a sidewall and a bottom of each fine concave portion has an oscillation waveform satisfying at least one of the following oscillation waveform conditions: the oscillation waveform is continuous; the oscillation waveform is a composite waveform of a plurality of oscillation waveforms, and the plurality of oscillation waveforms are in phase with each other; fine concave portions of a plurality of rows are formed on the substrate, and oscillation waveforms of adjacent fine concave portions are in phase with each other; and fine concave portions of a plurality of rows are formed on the substrate, and oscillation waveforms of the fine concave portions are in phase with each other for every two pitches.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of U.S. patentapplication Ser. No. 16/574,477 filed Sep. 18, 2019, which claimspriority of Japanese Patent Application No. 2018-177767 filed Sep. 21,2018, and Japanese Patent Application No. 2019-055111 filed Mar. 22,2019. The disclosures of the prior applications are hereby incorporatedby reference herein in their entirety.

TECHNICAL FIELD

The present disclosure relates to a microfabrication device, amicrofabrication method, a transfer mold, and a transfer object.

BACKGROUND

One of the microfabrication technologies is imprint technology by whicha master having a fine concave-convex structure formed on its surface ispressed against a resin sheet or the like to transfer the fineconcave-convex structure on the master to the resin sheet or the like.

A known master manufacturing method is a technique of forming aconcave-convex structure on a surface of a master substrate bylithography and dry etching using laser light. With this technique, aconcave-convex structure having an average period not greater thanvisible light wavelength can be formed on the surface of the mastersubstrate. Thus, an ultrafine concave-convex structure can be producedby this technique. Meanwhile, the technique needs a highly accuratemask, which causes an increase in master manufacturing cost. Moreover,since a large-scale manufacturing line is necessary, not only initialcost but also maintenance cost is high.

Another known master manufacturing method is a technique of forming aconcave-convex structure on a surface of a master substrate by cuttingwork using a cutting tool, as disclosed for example in PTL 1 to PTL 3.With this technique, a cutting tool having a tip (cutter) at its end isused to cut the master substrate, thus forming fine concave portions ina grid on the surface of the master substrate. The portions surroundedby the fine concave portions are fine convex portions. A fineconcave-convex structure is thus formed on the surface of the mastersubstrate. This technique has difficulty in forming such an ultrafineconcave-convex structure formed by the foregoing technique, but has theadvantage of being able to produce a master at relatively low cost. Withthe technique using the cutting tool, the cutting tool is moved relativeto the master substrate to cut the master substrate.

With the technique using the cutting tool, the master substrate may becut while oscillating the cutting tool, as disclosed for example inPTL 1. By such cutting, an oscillation waveform can be formed at thesidewall or the bottom of the fine concave portions. The cutting tool isoscillated for various purposes. For example, in the case of using thetransfer object for optical applications, improvement in the opticalproperties of the transfer object can be expected.

CITATION LIST Patent Literatures

PTL 1: JP 2015-71303 A

PTL 2: JP 2008-272925 A

PTL 3: JP 2004-344916 A

SUMMARY Technical Problem

However, as a result of closely examining the technique of oscillatingthe cutting tool, we learned that a defect, i.e. breaking of thecontinuity of the oscillation waveform, occurs on the surface of thetransfer object in some cases. Such a defect not only impairs theappearance of the transfer object, but also significantly decreases theoptical properties of the transfer object in the case where the transferobject is used for optical applications.

It could be helpful to provide a new and improved microfabricationdevice, microfabrication method, transfer mold, and transfer object thatcan suppress a defect.

Solution to Problem

According to an aspect of the present disclosure, provided is amicrofabrication device comprising: a tool mounting portion; a cuttingtool provided in the tool mounting portion, and configured to form fineconcave portions on a substrate; a driving portion configured to movethe tool mounting portion relative to the substrate; an oscillatorprovided in the tool mounting portion, and configured to oscillate thecutting tool in at least one of a depth direction and a surfacedirection of the substrate; and a controller configured to perform aplurality of sets of a cutting process of cutting the substrate whilemoving the tool mounting portion relative to the substrate andoscillating the cutting tool, wherein the controller is configured toperform the cutting process to satisfy at least one of:

a cutting condition (1) that oscillations at a start point and an endpoint of each set are in phase with each other; and

a cutting condition (2) that oscillations of the sets are in phase witheach other.

The cutting process may include a deep cutting process of repeatedlycutting a same part, with a cutting depth of a current set being deeperthan a cutting depth of a previous set.

The cutting process may include a parallel cutting process of performingcutting of a current set at a position adjacent to a cutting position ofa previous set.

The substrate may have a columnar or cylindrical shape, the drivingportion may include: a substrate driving portion configured to rotatethe substrate about a central axis of the substrate as a rotation axis;and a tool movement portion configured to move the tool mounting portionin a direction parallel to the rotation axis, and the controller may beconfigured to move the tool mounting portion relative to the substrate,by rotating the substrate and moving the tool mounting portion in thedirection parallel to the rotation axis.

According to another aspect of the present disclosure, provided is amicrofabrication method using the above-described microfabricationdevice, the microfabrication method comprising: providing the cuttingtool in the tool mounting portion; setting the tool mounting portion ata position facing the substrate; and performing a plurality of sets of acutting process of cutting the substrate while moving the tool mountingportion relative to the substrate and oscillating the cutting tool,wherein the cutting process is performed to satisfy at least one of:

a cutting condition (1) that oscillations at a start point and an endpoint of each set are in phase with each other; and

a cutting condition (2) that oscillations of the sets are in phase witheach other.

According to another aspect of the present disclosure, provided is atransfer mold comprising a substrate having one or more fine concaveportions formed on a surface thereof, wherein at least one of a sidewalland a bottom of each fine concave portion has an oscillation waveformsatisfying at least one of:

an oscillation waveform condition (1) that the oscillation waveform iscontinuous;

an oscillation waveform condition (2) that the oscillation waveform is acomposite waveform of a plurality of oscillation waveforms, and theplurality of oscillation waveforms are in phase with each other;

an oscillation waveform condition (3) that fine concave portions of aplurality of rows are formed on the substrate, and oscillation waveformsof adjacent fine concave portions are in phase with each other; and anoscillation waveform condition (4) that fine concave portions of aplurality of rows are formed on the substrate, and oscillation waveformsof the fine concave portions are in phase with each other for every twopitches.

The substrate may have a columnar or cylindrical shape.

According to another aspect of the present disclosure, provided is atransfer object comprising a substrate having one or more fine concaveportions formed on a surface thereof, wherein at least one of a sidewalland a bottom of each fine concave portion has an oscillation waveformsatisfying at least one of:

an oscillation waveform condition (1) that the oscillation waveform iscontinuous;

an oscillation waveform condition (2) that the oscillation waveform is acomposite waveform of a plurality of oscillation waveforms, and theplurality of oscillation waveforms are in phase with each other;

an oscillation waveform condition (3) that fine concave portions of aplurality of rows are formed on the substrate, and oscillation waveformsof adjacent fine concave portions are in phase with each other; and anoscillation waveform condition (4) that fine concave portions of aplurality of rows are formed on the substrate, and oscillation waveformsof the fine concave portions are in phase with each other for every twopitches.

Advantageous Effect

It is thus possible to suppress a defect by performing cutting thatsatisfies at least one of the cutting conditions (1) and (2).

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1A is a block diagram illustrating the overall structure of amicrofabrication device 1 according to one of the disclosed embodiments;

FIG. 1B is a block diagram illustrating the overall structure of amicrofabrication device 1 according to another one of the disclosedembodiments;

FIG. 2 is a sectional view illustrating the detailed structure of acutting device according to one of the disclosed embodiments;

FIG. 3 is a side view illustrating a helical cutting pattern which is anexample of a cutting pattern;

FIG. 4A is a side view illustrating a round slice cutting pattern whichis an example of a cutting pattern;

FIG. 4B is a side view illustrating a thrust cutting pattern which is anexample of a cutting pattern;

FIG. 4C is a side view illustrating an oblique thrust cutting patternwhich is an example of a cutting pattern;

FIG. 5 is a timing chart illustrating the relationship between therotation angle of a master substrate and the oscillation waveform of acutting tool;

FIG. 6A is a perspective view illustrating a specific example of fineconcave portions;

FIG. 6B is a plan view illustrating a specific example of fine concaveportions;

FIG. 6C is a plan view illustrating a specific example of fine concaveportions;

FIG. 7A is a perspective view illustrating a specific example of fineconcave portions;

FIG. 7B is a plan view illustrating a specific example of fine concaveportions;

FIG. 8A is a perspective view illustrating a specific example of fineconcave portions;

FIG. 8B is a plan view illustrating a specific example of fine concaveportions;

FIG. 9A is a flowchart of an example of a microfabrication method;

FIG. 9B is a flowchart of an example of a microfabrication method;

FIG. 10A is a perspective view illustrating an example of a master(transfer mold);

FIG. 10B is a perspective view illustrating an example of a master(transfer mold);

FIG. 10C is a perspective view illustrating an example of a master(transfer mold);

FIG. 11A is a perspective view illustrating an example of a transferobject;

FIG. 11B is a plan view illustrating an example of a transfer object;

FIG. 12 is a graph illustrating an example of the oscillation waveformof the cutting tool;

FIG. 13 is a graph illustrating an example of the oscillation waveformof the fine concave portions;

FIG. 14 is a graph illustrating an example of the oscillation waveformof the cutting tool;

FIG. 15 is a graph illustrating an example of the oscillation waveformof the fine concave portions;

FIG. 16 is a graph illustrating an example of the oscillation waveformof the cutting tool;

FIG. 17 is a graph illustrating an example of the oscillation waveformof the fine concave portions;

FIG. 18 is a graph illustrating an example of the oscillation waveformof the cutting tool;

FIG. 19 is a graph illustrating an example of the oscillation waveformof the cutting tool;

FIG. 20 is an SEM image of fine concave portions according to Example;

FIG. 21 is a microscope image of fine concave portions according toComparative Example; and

FIG. 22 is an SEM image of fine concave portions according toComparative Example.

DETAILED DESCRIPTION

Disclosed embodiments will be described in detail below, with referenceto the attached drawings. In the description and the drawings,components having substantially the same functional structures are giventhe same reference signs, and repeated description is omitted.

<1. Structure of Microfabrication Device>

The structure of a microfabrication device 1 according to an embodimentwill be described below, with reference to FIGS. 1A and 2 . FIG. 1A is ablock diagram illustrating the overall structure of the microfabricationdevice 1 that performs cutting while synchronizing the oscillation of acutting tool and the rotation of a master substrate (roll). Themicrofabrication device 1 cuts a master substrate (roll) 100 to formfine concave portions 110 on the surface of the master substrate 100. Amaster 120 illustrated in any of FIGS. 10A to 10C is thus produced. Themaster substrate 100 has a columnar or cylindrical shape. The master 120is, for example, a master for imprinting, and can be used as a transfermold to produce a transfer object 200 illustrated in FIGS. 11A and 11B.The master 120 and the transfer object 200 will be described later. Thestructure in FIG. 1A can be used, for example, in the case of formingthe below-described round slice cutting pattern or helical cuttingpattern.

The microfabrication device 1 includes a main rotation device 10(substrate driving portion), a follower rotation device 12, a cuttingdevice 20, and a control device 70.

The main rotation device 10, the central axis of the master substrate100, and the follower rotation device 12 are coaxially arranged. Themain rotation device 10 in FIG. 1A includes an encoder (notillustrated), and transmits rotation information about the rotationangle of the main rotation device 10 from the encoder to the controldevice 70. For example, the rotation information is a pulse signal. Eachtime the main rotation device 10 rotates a predetermined angle, the mainrotation device 10 transmits the rotation information to the controldevice 70. The predetermined angle is set based on the resolution of theencoder. For example, in the case where the resolution of the encoder is1440000 pulses, the predetermined angle may be 360/1440000°. In thisembodiment, the rotation direction of the main rotation device 10 (i.e.the circumferential direction of the master substrate 100) is y-axis,and the forward direction of the y-axis is counterclockwise as seen fromthe follower rotation device 12. The rotation speed (number ofrotations) of the master substrate 100 by the main rotation device 10 isnot limited, and may be, for example, 1 min⁻¹ to 100 min⁻¹.

The cutting device 20 includes a processing stage 30 (tool movementportion), a feed shaft 31, a tool mounting portion 40, an oscillator 50,and a cutting tool 60. The tool mounting portion 40 is mounted on theprocessing stage 30. The processing stage 30 is movable along the feedshaft 31. The feed shaft 31 extends in a direction parallel to therotation axis of the main rotation device 10 (i.e. the length directionof the master substrate 100) (that is, extends in the surface directionof the substrate, i.e. the direction parallel to the substrate surface).In this embodiment, the extending direction of the feed shaft 31 isx₁-axis, and the right direction in FIG. 1 is the forward direction ofthe x₁-axis. The processing stage 30 is also movable in a cutting axis(shaft) direction (the depth direction of the substrate). In thisembodiment, the cutting axis is z₁-axis, and the up direction in FIG. 1(the direction approaching the master substrate 100) is the forwarddirection of the z₁-axis. Hence, the processing stage 30 can move thetool mounting portion 40 (more specifically, the cutting tool 60 mountedin the tool mounting portion 40) in the x₁-axis direction or the z₁-axisdirection. Thus, in this embodiment, the main rotation device 10 rotatesthe master substrate 100 in the y-axis direction, and the processingstage 30 moves the tool mounting portion 40 in the x₁-axis or z₁-axisdirection. The tool mounting portion 40 accordingly moves relative tothe master substrate 100. The main rotation device 10 and the processingstage 30 thus function as a driving portion that moves the tool mountingportion 40 relative to the master substrate 100.

The tool mounting portion 40 is mounted on the processing stage 30, andmoves in the x₁-axis direction or the z₁-axis direction together withthe processing stage 30. The position of the tool mounting portion 40 ismeasured as a coordinate value on an x₁z₁ plane. The measurement isperformed by a displacement measuring instrument (not illustrated). Thedisplacement measuring instrument outputs x₁z₁ coordinate informationabout the measured x₁z₁ coordinate value of the tool mounting portion 40to the control device 70. The tool mounting portion 40 has a casestorage recess 41, and the oscillator 50 and the cutting tool 60 arestored in the case storage recess 41.

The oscillator 50 oscillates the cutting tool 60 in x₂-axis direction orz₂-axis direction. Thus, in this embodiment, a processing axis(x₂z₂-axis) different from the processing axis (x₁z₁-axis) by theprocessing stage 30 is created, and these axes are controlledindependently. Specifically, the oscillator 50 includes a tool storagecase 51, tool oscillation elements 52 a and 53 a, and displacementmeasuring instruments 52 b and 53 b.

The tool storage case 51 stores the cutting tool 60. The tool storagecase 51 is mounted in the case storage recess 41 formed in the toolmounting portion 40. The tool oscillation element 52 a connects the baseend (bottom surface) of the cutting tool 60 and the bottom surface ofthe tool storage case 51. The tool oscillation element 52 a oscillatesthe cutting tool 60 in the z₂-axis direction. The z₂-axis is an axisparallel to the z₁-axis, and the forward direction of the z₂-axis is thesame as the forward direction of the z₁-axis. The type of the tooloscillation element 52 a is not limited. The tool oscillation element 52a may be any device capable of moving the cutting tool 60 in the z₂-axisdirection, but is preferably a linear motion stage of high accuracy andhigh rigidity. Preferable examples of the tool oscillation element 52 ainclude a piezoelectric element, a linear motor, and an ultrasonicelement. Particularly preferable examples of the tool oscillationelement 52 a include a piezoelectric element. The oscillation of thetool oscillation element 52 a is controlled by the control device 70.

The displacement measuring instrument 52 b measures the displacement ofthe oscillation of the cutting tool 60 in the z₂-axis direction, as a z₂coordinate value. The displacement measuring instrument 52 b may be anydevice capable of measuring the displacement of the oscillation of thecutting tool 60 in the z₂-axis direction, but is preferably a device ofhigh accuracy and small size with little hysteresis. Preferable examplesof the displacement measuring instrument 52 b include measuringinstruments of capacitance type, laser interference type, andpressure-sensitive dial indicator type. The displacement measuringinstrument 52 b outputs z₂ coordinate information about the measured z₂coordinate value to the control device 70.

The tool oscillation element 53 a extends in the x₂-axis direction, andconnects the outer wall surface of the tool storage case 51 and theouter wall surface of the case storage recess 41. The tool oscillationelement 53 a moves the cutting tool 60 in the x₂-axis direction. Thex₂-axis is an axis parallel to the x₁-axis, and the forward direction ofthe x₂-axis is the same as the forward direction of the x₁-axis.Preferable examples of the tool oscillation element 53 a include apiezoelectric element, a linear motor, and an ultrasonic element.Particularly preferable examples of the tool oscillation element 53 ainclude a piezoelectric element. The oscillation of the tool oscillationelement 53 a is controlled by the control device 70.

The displacement measuring instrument 53 b measures the displacement ofthe oscillation of the cutting tool 60 in the x₂-axis direction, as anx₂ coordinate value. The displacement measuring instrument 53 b may beany device capable of measuring the displacement of the cutting tool 60in the x₂-axis direction, but is preferably a device of high accuracyand small size with little hysteresis. Preferable examples of thedisplacement measuring instrument 53 b include measuring instruments ofcapacitance type, laser interference type, and pressure-sensitive dialindicator type. The displacement measuring instrument 53 b outputs x₂coordinate information about the measured x₂ coordinate value to thecontrol device 70. In this embodiment, the x₂z₂ coordinate value of thecutting tool 60 is the x₂z₂ coordinate value of the below-described tooltip 63.

The cutting tool 60 is movably provided in the tool mounting portion 40.The cutting tool 60 includes a tool body 61 and a tool cutter (tip) 62.The tool body 61 is a rodlike member extending in the z₂-axis direction.The bottom surface of the cutting tool 60 is preferably smooth, becausethe above-described tool oscillation element 52 a and the like aremounted on the bottom surface. The tool cutter 62 is attached to the endof the tool body 61. The tool cutter 62 has a taper shape. The tool tip63 (point of action) at the tip of the tool cutter 62 is pressed againstthe master substrate 100 to cut the master substrate 100. The shape ofthe tool tip 63 is not limited, and may be, for example, a rectangle ora curved surface. Thus, a fine concave portion 110 is formed on thesurface of the master substrate 100. The shape of the bottom 110 a ofthe fine concave portion 110 reflects the shape of the tool tip 63. Thematerial of the tool cutter 62 may be, for example, diamond, cementedcarbide, high-speed tool steel, or cubic boron nitride (CBN). The toolcutter 62 is produced by polishing such material. The tool cutter 62 maybe produced by laser radiation, ion milling, or the like.

FIG. 2 , etc. schematically illustrate the cutting tool 60, and theshape of the cutting tool 60 is not limited to that illustrated in FIG.2 , etc. For example, the tool body 61 and the tool cutter 62 may beformed integrally. Although one set of the tool mounting portion 40, theoscillator 50, and the cutting tool 60 is formed on the processing stage30 in the example in FIG. 2 , a plurality of sets of these members maybe formed on the processing stage 30.

The control device 70 in FIG. 1A is connected to the main rotationdevice 10 and the cutting device 20 by communication cables or the like,and can communicate information (e.g. the rotation information of themain rotation device 10, the x₁z₁ coordinate information of the toolmounting portion 40, the x₂z₂ coordinate information of the cutting tool60) with these devices.

Specifically, the control device 70 includes a control calculator 71, acontroller 72, and an amplifier 73. The control device 70 includes, as ahardware structure, a CPU (central processing unit, i.e. processor), RAM(random access memory), ROM (read only memory), a hard disk, variousinput operation devices (keyboard, mouse, etc.), a display, an arbitrarywaveform generator, a communication device, and the like. The ROM storesinformation necessary for the process by the control device 70, such asa processing program. The CPU reads the processing program stored in theROM, and executes it. The arbitrary waveform generator is a device forgenerating an arbitrary waveform with an arbitrary frequency andvoltage, and is used to output the x₂z₂ coordinate value of the cuttingtool 60 described later.

The control calculator 71 in FIG. 1A calculates the x₁z₁ coordinatevalue of the tool mounting portion 40 and the x₂z₂ coordinate value ofthe cutting tool 60 (roughly, the oscillation waveform in the x₂-axisdirection or the z₂-axis direction), based on the information providedfrom the main rotation device 10. The control calculator 71 outputscoordinate information about the calculated coordinate value to thecontroller 72.

The controller 72 controls the operation of the cutting device 20 basedon the coordinate information provided from the control calculator 71.Specifically, the controller 72 generates oscillation controlinformation for moving the cutting tool 60 to the x₂z₂ coordinate valuecalculated by the control calculator 71, and outputs the oscillationcontrol information to the amplifier 73. The amplifier 73 amplifies theoscillation control information, and outputs the amplified oscillationcontrol information to the oscillator 50. The tool oscillation elements52 a and 53 a in the oscillator 50 operate based on the oscillationcontrol information. The cutting tool 60 is thus oscillated. Moreover,the controller 72 controls the processing stage 30 based on thecoordinate information, to move the tool mounting portion 40 in thex₁-axis direction or the z₁-axis direction. Consequently, fine concaveportions 110 are formed on the master substrate 100 in a desired cuttingpattern. The control by the controller 72 will be described in detaillater.

FIG. 1B is a block diagram illustrating the overall structure of themicrofabrication device 1 that performs cutting while synchronizing theoscillation of the cutting tool and the coordinate of the feed shaft ofthe cutting tool. The overall structure in FIG. 1B is approximately thesame as that in FIG. 1A, except that the synchronization method for theoscillation of the cutting tool is different. The structure in FIG. 1Bcan be used, for example, in the case of forming the below-describedthrust cutting pattern or oblique thrust cutting pattern. Thedifferences from FIG. 1A will be mainly described below.

The feed shaft 31 in FIG. 1B includes a scale (not illustrated), andtransmits position information about the coordinate of the feed shaft 31from the scale to the control device 70. For example, the positioninformation is a pulse signal. Each time the feed shaft 31 moves apredetermined distance, the position information can be transmitted tothe control device 70. The feed speed (movement speed) of the feed shaft31 is not limited. The feed speed may be 1,000 mm/min to 20,000 mm/min,and is desirably 10,000 mm/min.

The control device 70 in FIG. 1B is connected to the feed shaft 31 andthe cutting device 20 by communication cables or the like, and cancommunicate information (e.g. the position information of the feed shaft31, the x₁z₁ coordinate information of the tool mounting portion 40, thex₂z₂ coordinate information of the cutting tool 60) with these devices.

The control calculator 71 in FIG. 1B calculates the z₁ coordinate valueof the tool mounting portion 40 and the x₂z₂ coordinate value of thecutting tool 60 (roughly, the oscillation waveform in the x₂-axisdirection or the z₂-axis direction), based on the information providedfrom the feed shaft 31. The control calculator 71 outputs coordinateinformation about the calculated coordinate value to the controller 72.

The controller 72 controls the operation of the cutting device 20 basedon the coordinate information provided from the control calculator 71.Specifically, the controller 72 generates oscillation controlinformation for moving the cutting tool 60 to the x₂z₂ coordinate valuecalculated by the control calculator 71, and outputs the oscillationcontrol information to the amplifier 73. The amplifier 73 amplifies theoscillation control information, and outputs the amplified oscillationcontrol information to the oscillator 50. The tool oscillation elements52 a and 53 a in the oscillator 50 operates based on the oscillationcontrol information. The cutting tool 60 is thus oscillated. Moreover,the controller 72 controls the processing stage 30 based on thecoordinate information, to move the tool mounting portion 40 in thez₁-axis direction. Consequently, fine concave portions 110 are formed onthe master substrate 100 in a desired cutting pattern. The control bythe controller 72 will be described in detail later.

<2. Overview of Process by Controller>

An overview of the process by the controller 72 will be described below,with reference to FIGS. 3, 4A, 4B, and 4C. The controller 72 controlsthe operation of the cutting device 20, as described above. Morespecifically, the controller 72 performs a plurality of sets of acutting process. The cutting process is a process of cutting the mastersubstrate 100 while moving the tool mounting portion 40 relative to themaster substrate 100 and oscillating the cutting tool 60. By moving thetool mounting portion 40 relative to the master substrate 100, the fineconcave portions 110 are formed on the master substrate 100, thusachieving a helical cutting pattern illustrated in FIG. 3 , a roundslice cutting pattern illustrated in FIG. 4A, a thrust cutting patternillustrated in FIG. 4B, or an oblique thrust cutting pattern illustratedin FIG. 4C. The helical cutting pattern, the round slice cuttingpattern, the thrust cutting pattern, and the oblique thrust cuttingpattern are each an example of a parallel cutting process of performingthe cutting of the current set at a position adjacent to the cuttingposition of the previous set. Each fine concave portion 110 has a bottom110 a and a sidewall 110 b. The boundary part between adjacent fineconcave portions 110 is a fine convex portion 111.

The helical cutting pattern is a pattern in which the fine concaveportions 110 are helically formed on the master substrate 100. Thehelical cutting pattern is produced roughly by the following process.While rotating the master substrate 100, the tool mounting portion 40 ismoved in the x₁-axis direction relatively slowly. The helical cuttingpattern is thus formed on the master substrate 100. In the case offorming the helical cutting pattern on the master substrate 100, cuttingfor one or more rounds of the master substrate 100 is one set of thecutting process. By performing a plurality of sets of the cuttingprocess, the controller 72 forms the fine concave portions 110 inhelical shape from one end to the other end of the master substrate 100.After forming the helical cutting pattern on the master substrate 100,the helical cutting pattern may be formed again with the helicalinclination direction being inverted. This pattern is also referred toas a cross helical cutting pattern.

The round slice cutting pattern is a pattern in which the fine concaveportions 110 are formed along the circumferential direction of themaster substrate 100. The extending direction of the fine concaveportions 110 is perpendicular to the axis direction of the mastersubstrate 100. The round slice cutting pattern is produced roughly bythe following process. Having fixed the x₁ coordinate of the toolmounting portion 40, the master substrate 100 is rotated. The fineconcave portion 110 is thus formed on the master substrate 100. Afterthe fine concave portion 110 is formed on the master substrate 100 forone round, the tool mounting portion 40 is moved in the x₁ direction byone pitch, and the same process is repeated. Herein, the term “pitch”denotes the distance between adjacent fine concave portions 110, thatis, the distance between the center lines of the fine concave portions110 in the width direction. The round slice cutting pattern is thusformed on the master substrate 100. In the case of forming the roundslice cutting pattern on the master substrate 100, cutting for one ormore rounds of the master substrate 100 is one set of the cuttingprocess. By performing a plurality of sets of the cutting process, thecontroller 72 forms the fine concave portions 110 in round slice shapefrom one end to the other end of the master substrate 100.

The thrust cutting pattern is a pattern in which the fine concaveportions 110 are formed along the axis direction of the master substrate100. The extending direction of the fine concave portions 110 isparallel to the axis direction of the master substrate 100. The thrustcutting pattern is produced roughly by the following process. Withoutrotating the master substrate 100, the tool mounting portion 40 is movedin the x₁-axis direction. The fine concave portion 110 is thus formed onthe master substrate 100. After the fine concave portion 110 is formedfor one row from one end to the other end of the master substrate 100,the tool mounting portion 40 is moved to the start position, and themaster substrate 100 is rotated by one pitch in the forward direction orbackward direction of the y-axis and stopped. The same process is thenrepeated. Herein, the term “pitch” denotes the distance between adjacentfine concave portions 110, that is, the distance between the centerlines of the fine concave portions 110 in the width direction. Thethrust cutting pattern is thus formed on the master substrate 100. Inthe case of forming the thrust cutting pattern on the master substrate100, cutting for one or more rows of the master substrate 100 is one setof the cutting process. By performing a plurality of sets of the cuttingprocess, the controller 72 forms the fine concave portions 110 of aplurality of rows parallel to the axis direction of the master substrate100 on the circumferential surface of the master substrate 100.

The oblique thrust cutting pattern is a pattern in which the fineconcave portions 110 are formed at an inclination with respect to theaxis direction of the master substrate 100. The oblique thrust cuttingpattern is produced roughly by the following process. While rotating themaster substrate 100 relatively slowly, the tool mounting portion 40 ismoved in the x₁-axis direction. The fine concave portion 110 is thusformed on the master substrate 100. After the fine concave portion 110is formed for one row from one end to the other end of the mastersubstrate 100 (or after the fine concave portion 110 is formed for oneor more rounds on the master substrate 100), the tool mounting portion40 is moved to the start position, and the start rotation angle (ycoordinate) of the master substrate 100 is shifted by one pitch in theforward direction or backward direction of the y-axis and stopped. Thesame process is then repeated. The oblique thrust cutting pattern isthus formed on the master substrate 100. In the case of forming theoblique thrust cutting pattern on the master substrate 100, cutting forone or more rows of the master substrate 100 (or cutting for one or morerounds of the master substrate 100) is one set of the cutting process.By performing a plurality of sets of the cutting process, the controller72 forms the fine concave portions 110 of a plurality of rows at aninclination with respect to the axis direction of the master substrate100 on the circumferential surface of the master substrate 100.

The inclination angle of the fine concave portions 110 in the helicalcutting pattern with respect to the direction perpendicular to the axisdirection of the master substrate 100 is typically more than 0° and lessthan 1°. The inclination angle of the fine concave portions 110 in theoblique thrust cutting pattern with respect to the directionperpendicular to the axis direction of the master substrate 100 istypically 1° or more and less than 180° (i.e. the inclination angle withrespect to the axis direction of the master substrate 100 is typicallymore than 0° and 179° or less). These inclination angle ranges are,however, not a limitation, as a helical cutting pattern or an obliquethrust cutting pattern is selected based on the load of the cuttingtool, the cutting time, and the like. For example, in this embodiment, ahelical cutting pattern whose inclination angle with respect to thedirection perpendicular to the axis direction of the master substrate100 is more than 1° may be selected.

The controller 72 may perform a deep cutting process of repeatedlycutting the same part, in each cutting pattern. In the case ofperforming the deep cutting process, any of the foregoing cuttingpatterns is repeatedly formed with different cutting depths. Cutting ateach cutting depth is therefore one set of the deep cutting process. Thecontroller 72 sets the cutting depth of the current set to be deeperthan the cutting depth of the previous set.

The controller 72 performs cutting while oscillating the cutting tool60, in each cutting pattern. Consequently, at least one of the bottom110 a and the sidewall 110 b of the fine concave portion 110 has anoscillation waveform.

Moreover, the controller 72 performs the cutting process so as tosatisfy at least one of the following cutting conditions (1) and (2).Preferably, the controller 72 performs cutting so as to satisfy both ofthe cutting conditions (1) and (2). Herein, “the oscillations of thesets are in phase with each other” in the cutting condition (2) meansthat the phase at the same rotation angle (y coordinate) of the mastersubstrate 100 is the same among the sets.

Cutting condition (1): the oscillations at the start point and the endpoint of each set are in phase with each other.

Cutting condition (2): the oscillations of the sets are in phase witheach other.

As an example, the cutting conditions (1) and (2) in the case of usingthe structure in FIG. 1A will be described below, with reference to FIG.5 . In FIG. 5 , the horizontal axis represents time. The upper graph L1represents the output timing of the rotation information of the mastersubstrate 100. The rotation angle of the master substrate 100 at timest0, t1, t2, t3, and t4 is respectively 0°, 90°, 180°, 270°, and 360°(=0°). The output timing of rotation information indicating that therotation angle of the master substrate 100 is 0° (=360°) is illustratedhere, to facilitate understanding. The lower graphs L2 and L3 representthe oscillation waveform of the cutting tool 60 (i.e. the z₂ coordinatevalue of the cutting tool 60 at each time). In the example in FIG. 5 ,cutting for one turn of the master substrate 100 is one set. That is,the graph L2 represents the oscillation waveform of the current set, andthe graph L3 represents the oscillation waveform of the next set.

As illustrated in FIG. 5 , the oscillations at the start point and theend point of each set are in phase with each other (0° at both points).The cutting condition (1) is thus satisfied. Moreover, the oscillationsof the sets are in phase with each other. For example, the phase at thestart point of each set is 0°, and thus the sets are in phase with eachother at the same rotation angle (y coordinate value). The cuttingcondition (2) is thus satisfied.

The controller 72 performs cutting while synchronizing the oscillationof the cutting tool 60 and the rotation of the master substrate 100 inthis way. As a result, oscillation continuity is maintained among thesets without a defect. For example, in each of the foregoing cuttingpatterns, the oscillation waveforms are in phase with each other forevery one or more sets. That is, the oscillation waveforms of adjacentfine concave portions 110 may be in phase with each other. In thehelical cutting pattern (and the oblique thrust cutting pattern), inaddition to the above, the oscillation waveforms of the fine concaveportions 110 are in phase with each other at the connection part betweenthe sets. In the round slice cutting pattern, in addition to the above,the oscillation waveforms of the fine concave portions 110 are in phasewith each other at the connection part of the start point and the endpoint of the set. In the thrust cutting pattern (and the oblique thrustcutting pattern), in addition to the above, the oscillation waveforms ofthe fine concave portions 110 are in phase with each other at the startpoint and the end point of the set. Further, in the case of performingthe deep cutting process, the oscillations of the deep cutting sets arein phase with each other, so that the oscillation waveform of the fineconcave portion 110 accurately reflects the oscillation waveform of thecutting tool 60 in each set. To enable the controller 72 to perform theabove-described process, the control calculator 71 calculates the x₁z₁coordinate value of the tool mounting portion 40, the x₂z₂ coordinatevalue of the cutting tool 60, and the like. The oscillation waveform isnot limited. For example, the oscillation waveform is a sine waveform.The oscillation waveform is, however, not limited to this, and may beany oscillation waveform. For example, the oscillation waveform may be atrapezoidal waveform. In this embodiment, the term “defect” denotes apart at which the continuity of the oscillation waveform breaks (a partwhere the shape is disturbed, such as a difference in level), which isobservable with the naked eye or some kind of microscope (e.g. ascanning electron microscope or a microscope).

Furthermore, in this embodiment, the processing axis (x₂z₂-axis)different from the processing axis (x₁z₁-axis) by the processing stage30 is created, and these axes are controlled independently to controlthe position of the cutting tool 60. Therefore, point group data isunnecessary. The point group data is the three-dimensional position dataof the cutting tool 60. For example, the cutting tool 60 can be moved byattaching the cutting tool 60 to an NC machine and controlling the NCmachine according to point group data. However, microfabrication isdifficult in such a case. Suppose, for example, the pitch of the helicalcutting pattern is 0.01 mm, and the number of pieces of point group datais 10000 per one pitch. In this case, an instruction (an instruction tomove the cutting tool 60) needs to be issued per 0.01/10000 mm in thex₁-axis direction (feed direction) of the cutting tool 60. ConventionalNC machines cannot operate at such a resolution. Accordingly, the numberof pieces of point group data per one pitch needs to be reduced, whichcauses a decrease in processing accuracy. In this embodiment, pointgroup data is unnecessary, and microfabrication is possible.

<3. Specific Examples of Process by Controller>

Specific examples of the process will be described below, with referenceto FIGS. 6A to 8B. FIGS. 6A and 6B illustrate an example of the roundslice cutting pattern. In this example, the controller 72 performscutting along the foregoing round slice cutting pattern. The controller72 also oscillates the cutting tool 60 in the z₂-axis direction so as tosatisfy the foregoing cutting condition (1) and/or (2). Here, cuttingfor one round of the master substrate 100 is one set of the cuttingprocess. Further, the controller 72 overlaps the cutting regions by thecutting tool 60 between the pitches of the fine concave portions 110. Asa result, the fine concave portions 110 illustrated in FIGS. 6A and 6Bare formed. The bottom 110 a and the sidewall 110 b of the fine concaveportion 110 and the fine convex portion 111 are linear in a plan view.Meanwhile, the height of the upper end of the fine convex portion 111oscillates in the z₂-axis direction. Moreover, the oscillation waveformsof adjacent fine convex portions 111 are in phase with each other. Inthe case where the cutting regions by the cutting tool 60 are separatedbetween the pitches of the fine concave portions 110, the fine concaveportions 110 illustrated in FIG. 6C are formed. In this example, thebottom 110 a of the fine concave portion 110 is linear in a plan view,whereas the shape of the sidewall 110 b of the fine concave portion 110is an oscillation waveform in a plan view. The oscillation waveforms ofthe sidewalls 110 b of adjacent fine concave portions 110 are in phasewith each other. Such an oscillation waveform is formed because the toolcutter 62 of the cutting tool 60 has a taper shape.

FIGS. 7A and 7B illustrate an example of the round slice cuttingpattern. In this example, the controller 72 performs cutting along theforegoing round slice cutting pattern. The controller 72 also oscillatesthe cutting tool 60 in the x₂-axis direction so as to satisfy theforegoing cutting condition (1) and/or (2). Here, cutting for one roundof the master substrate 100 is one set of the cutting process. As aresult, the fine concave portions 110 illustrated in FIGS. 7A and 7B areformed. The bottom 110 a and the sidewall 110 b of the fine concaveportion 110 and the fine convex portion 111 are shaped as an oscillationwaveform in a plan view. The oscillation waveforms of adjacent fineconcave portions 110 are in phase with each other.

FIGS. 8A and 8B illustrate an example of the round slice cuttingpattern. In this example, the controller 72 performs cutting along theforegoing round slice cutting pattern. The controller 72 also oscillatesthe cutting tool 60 in the z₂-axis direction so as to satisfy theforegoing cutting condition (1) and/or (2). Here, cutting for two roundsof the master substrate 100 is one set of the cutting process. Further,the controller 72 makes the cutting regions by the cutting tool 60adjacent to each other between the pitches of the fine concave portions110. As a result, the fine concave portions 110 illustrated in FIGS. 8Aand 8B are formed. The bottom 110 a of the fine concave portion 110 islinear in a plan view, and the sidewall 110 b of the fine concaveportion 110 and the fine convex portion 111 are shaped as an oscillationwaveform in a plan view. Meanwhile, the height of the upper end of thefine convex portion 111 oscillates in the z₂-axis direction. Moreover,the oscillation waveforms of fine convex portions 111 are in phase witheach other for every two pitches (i.e. every two rounds). Theoscillation waveforms of adjacent fine convex portions 111 are 180° outof phase with each other. Such an oscillation waveform is formed becausethe tool cutter 62 of the cutting tool 60 has a taper shape. The samecutting may be performed for the helical cutting pattern. In this case,too, cutting for two rounds of the master substrate 100 is set as oneset of the cutting process. FIG. 20 illustrates the surface shape of themaster 120 produced (SEM photograph). As illustrated in FIG. 20 , nodefect is observed.

While the above describes specific examples of the process by thecontroller 72, the process by the controller 72 is not limited to theseexamples. In each of the specific examples, the controller 72 mayperform the deep cutting process so as to satisfy the cutting condition(1) and/or (2). The controller 72 may perform cutting so as to satisfythe cutting condition (1) and/or (2) in the helical cutting pattern, thethrust cutting pattern, or the oblique thrust cutting pattern.

<4. Errors>

It is very important in this embodiment that the phase of theoscillation of the cutting tool is the same among the sets or at thestart point and the end point of the same set, as indicated by thecutting conditions (1) and (2). In actual cutting, however, it isdifficult to have the exactly same oscillation phase. We accordinglyconducted study on acceptable errors, and found out that the defect issuppressed if an error is within a certain acceptable range.

For example, in the round slice cutting pattern, an error of the cuttingcondition (1) can occur. Specifically, an error that the y coordinatevalue of the start point and the y coordinate value of the end pointoverlap in any set (i.e. the y coordinate value of the end point is moreforward on the y-axis than the y coordinate value of the start point)can occur (case 1). Moreover, an error that the end point of cuttingdoes not reach the start point of cutting in any set (i.e. the ycoordinate value of the end point is more backward on the y-axis thanthe y coordinate value of the start point) can occur (case 2). In case1, no defect occurs if the deviation (difference in level) of thecutting depth associated with the overlap is less than 0.5 μm. In case2, no defect occurs if the length of a flat part between the start pointand the end point in the y-axis direction is less than 0.5 μm. The rangein which the depth of the difference in level or the length of the flatpart is less than 0.5 μm is therefore the acceptable error range. Ifthese errors are within the acceptable error range, the cuttingcondition (1) can be satisfied.

In the helical cutting pattern, the round slice cutting pattern, thethrust cutting pattern, and the oblique thrust cutting pattern, an errorthat the oscillation waveforms of adjacent fine concave portions 60 areout of phase with each other can occur, as an error of the cuttingcondition (2). No defect occurs if this error is less than 5°. The rangein which the phase difference is less than 5° is therefore theacceptable error range. In the deep cutting process, an error that theoscillations of sets are out of phase with each other can occur, as anerror of the cutting condition (2). No defect occurs if this error isless than 5°. The range in which the phase difference is less than 5° istherefore the acceptable error range. If these errors are within theacceptable error range, the cutting condition (2) can be satisfied.

<5. Microfabrication Method Using Microfabrication Device>

An example of a microfabrication method using the microfabricationdevice 1 will be described below, with reference to a flowchart in FIG.9A. An operator produces a master through the following process.

In step S10, the operator prepares the master substrate 100. The shapeof the master substrate 100 is not limited. For example, the shape ofthe master substrate 100 is columnar or cylindrical. The material of themaster substrate 100 is not limited, but is preferably an amorphousmaterial or a material with a small particle size in order to maintainthe smoothness of the processing surface. For example, the mastersubstrate 100 is preferably made of copper, a copper alloy, nickel, anickel alloy, austenitic stainless steel, or duralumin. Specificexamples include S45C and SUS304.

A coating layer may be formed on the surface of the master substrate100. In this case, the fine concave portions 110 are formed on thecoating layer. The method of forming the coating layer on the surface ofthe master substrate 100 is not limited, and may be, for example, thefollowing method. First, the operator coats the circumferential surfaceof the master substrate 100 with the material (e.g. Cu, Ni—P alloy) ofthe coating layer. The type of the coating is not limited, and may be,for example, electroplating. The coating layer immediately after theformation often has a rough surface.

Accordingly, after forming the coating layer on the circumferentialsurface of the master substrate 100, the coating layer may be subjectedto smoothing treatment. The smoothing treatment is not limited. Forexample, a smoothing bit (a bit with a cutter of a curved surface shape)may be used. With this method, for example, the operator attaches themaster substrate 100 with the coating layer formed thereon and thesmoothing bit to a precision lathe. The operator then rotates the mastersubstrate 100 about the central axis of the master substrate 100 as therotation axis. The operator then presses the cutter of the smoothing bitagainst one end of the coating layer in the axis direction. The axisdirection herein denotes the central axis direction of the mastersubstrate 100. After this, while rotating the master substrate 100, theoperator moves the smoothing bit from the one end in the axis directionto the other end in the axis direction. The coating layer is smoothed asa result of this process.

The operator then mounts the master substrate 100 on the main rotationdevice 10.

In step S20, the operator sets the tool mounting portion 40 on theprocessing stage 30. The operator also provides the oscillator 50 in thetool mounting portion 40. Alternatively, the tool mounting portion 40provided with the oscillator 50 beforehand may be prepared. In step S30,the operator stores the cutting tool 60 in the tool storage case 51.

In step S40, the operator sets the control system. In step S50, theoperator sets the rotation speed of the main rotation device 10.Specifically, the operator inputs information necessary for obtaining adesired fine concave-convex pattern, to the control device 70. Examplesof such information include the rotation speed of the master substrate100, the movement locus and movement speed of the tool mounting portion40, and the cutting depth, oscillation direction, oscillation waveform,oscillation frequency, and oscillation amplitude of the cutting tool 60.For example, the controller 72 displays an input screen on a display.The operator inputs the foregoing information using an input operationdevice. In the case where control that satisfies the cutting condition(1) and/or (2) cannot be performed with the provided information, thecontroller 72 may prompt the operator to correct the information. Thecontroller 72 may display an example of a numeric value necessary tosatisfy the cutting condition (1) and/or (2), on the input screen. Thecontroller 72 outputs information about the rotation speed of the mastersubstrate 100 to the main rotation device 10.

In step S60, the main rotation device 10 starts the rotation of themaster substrate 100. The main rotation device 10 then outputs rotationinformation about the rotation angle of the master substrate 100 to thecontrol device 70.

In steps S70 and S80, the controller 72 drives the processing stage 30to change the position of the tool mounting portion 40 in each of thex₁-axis direction and the z₁-axis direction from the start position.That is, the tool mounting portion 40 is set at a position facing themaster substrate 100.

In step S90, the operator starts the operation of the control system(i.e. the microfabrication device 1). In step S100, the control device70 starts the synchronous operation of the oscillator 50. In detail, thecontrol calculator 71 calculates the x₂z₂ coordinate value of thecutting tool 60, triggered by the rotation information provided from themain rotation device 10. Here, the control calculator 71 calculates thex₂z₂ coordinate value of the cutting tool 60 so that the oscillation ofthe cutting tool 60 satisfies at least one of the cutting conditions (1)and (2). The control calculator 71 outputs coordinate information aboutthe calculated coordinate value to the controller 72. The controller 72generates oscillation control information for moving the cutting tool 60to the coordinate value calculated by the control calculator 71, andoutputs the oscillation control information to the amplifier 73. Theamplifier 73 amplifies the oscillation control information, and outputsthe amplified oscillation control information to the oscillator 50. Thetool oscillation elements 52 a and 53 a in the oscillator 50 operatebased on the oscillation control information. Thus, the cutting tool 60oscillates synchronously with the rotation of the master substrate 100.

In step S110, the control calculator 71 calculates the x₁z₁ coordinatevalue of the tool mounting portion 40 based on the rotation informationprovided from the main rotation device 10. Here, the control calculator71 calculates the x₁z₁ coordinate value of the tool mounting portion 40so as to satisfy at least one of the cutting conditions (1) and (2). Thecontrol calculator 71 outputs coordinate information about thecalculated coordinate value to the controller 72. The controller 72moves the tool mounting portion 40 according to the coordinateinformation, the processing program, and the information input by theoperator. Thus, grooving is performed in step S120. That is, the fineconcave portions 110 are formed on the surface of the master substrate100. In detail, the controller 72 performs a plurality of sets of thecutting process of cutting the master substrate 100 while moving thetool mounting portion 40 relative to the master substrate 100 andoscillating the cutting tool 60. The controller 72 performs the cuttingprocess so as to satisfy at least one of the cutting conditions (1) and(2). In the case where the value of the coordinate information providedfrom, for example, the displacement measuring instrument 52 b or 53 bdiffers from the instruction, the controller 72 may perform anabnormality process (such as stopping the operation and notifying theoperator).

In step S130, the cutting (processing) of the master substrate 100 iscompleted. That is, cutting from one end to the other end of the mastersubstrate 100 is completed. In the case of performing the deep cuttingprocess, the following processes of steps S140 to S160 are furtherperformed. In step S140, the operator replaces the cutting tool 60according to need. In step S150, the operator positions the cutting tool60. Specifically, the cutting tool 60 is positioned so that the cuttingdepth is deeper than that in the deep cutting process of the previousset. Subsequently, the operator repeatedly performs the processes ofsteps S70 to S130. This process then ends.

Another example of the microfabrication method using themicrofabrication device 1 will be described below, with reference to aflowchart in FIG. 9B. The operator produces a master through thefollowing process.

Steps S10 to S30 are the same as those described above.

In step S40, the operator sets the control system. In step S50′, theoperator sets feed speed of the feed shaft 31. Specifically, theoperator inputs information necessary for obtaining a desired fineconcave-convex pattern, to the control device 70. Examples of suchinformation include the feed speed of the feed shaft 31, the movementlocus of the tool mounting portion 40, and the cutting depth,oscillation direction, oscillation waveform, oscillation frequency, andoscillation amplitude of the cutting tool 60. For example, thecontroller 72 displays an input screen on a display. The operator inputsthe foregoing information using an input operation device. In the casewhere control that satisfies the cutting condition (1) and/or (2) cannotbe performed with the provided information, the controller 72 may promptthe operator to correct the information. The controller 72 may displayan example of a numeric value necessary to satisfy the cutting condition(1) and/or (2), on the input screen. The controller 72 outputsinformation about the feed speed of the feed shaft 31 to the feed shaft31.

In steps S70, S75, and S80, the controller 72 drives the processingstage to change the position of the tool mounting portion 40 in each ofthe x₁-axis direction and the z₁-axis direction from the start position.That is, the tool mounting portion 40 is set at a position facing themaster substrate 100. The controller 72 also moves the rotation axis ofthe master substrate 100 to the start position (i.e. the start rotationangle).

In step S90, the operator starts the operation of the control system(i.e. the microfabrication device 1). In step S100, the control device70 starts the synchronous operation of the oscillator 50. In detail, thecontrol calculator 71 calculates the x₂z₂ coordinate value of thecutting tool 60, triggered by the coordinate information (x₁ coordinatevalue) of the feed shaft 31. Here, the control calculator 71 calculatesthe x₂z₂ coordinate value of the cutting tool 60 so that the oscillationof the cutting tool 60 satisfies at least one of the cutting conditions(1) and (2). The control calculator 71 outputs coordinate informationabout the calculated coordinate value to the controller 72. Thecontroller 72 generates oscillation control information for moving thecutting tool 60 to the coordinate value calculated by the controlcalculator 71, and outputs the oscillation control information to theamplifier 73. The amplifier 73 amplifies the oscillation controlinformation, and outputs the amplified oscillation control informationto the oscillator 50. The tool oscillation elements 52 a and 53 a in theoscillator 50 operate based on the oscillation control information.Thus, the cutting tool 60 oscillates synchronously with the coordinateof the feed shaft 31.

In step S110, the control calculator 71 calculates the z₁ coordinatevalue of the tool mounting portion 40 based on the position informationprovided from the main feed shaft 31. Here, the control calculator 71calculates the z₁ coordinate value of the tool mounting portion 40 so asto satisfy at least one of the cutting conditions (1) and (2). Thecontrol calculator 71 outputs coordinate information about thecalculated coordinate value to the controller 72. The controller 72moves the tool mounting portion 40 according to the coordinateinformation, the processing program, and the information input by theoperator. Thus, grooving is performed in step S120. That is, the fineconcave portions 110 are formed on the surface of the master substrate100. In detail, the controller 72 performs a plurality of sets of thecutting process of cutting the master substrate 100 while moving thetool mounting portion 40 relative to the master substrate 100 andoscillating the cutting tool 60. The controller 72 performs the cuttingprocess so as to satisfy at least one of the cutting conditions (1) and(2). In the case where the value of the coordinate information providedfrom, for example, the displacement measuring instrument 52 b or 53 bdiffers from the instruction, the controller 72 may perform anabnormality process (such as stopping the operation and notifying theoperator).

In step S130, the cutting (processing) of the master substrate 100 iscompleted. That is, cutting from one end to the other end of the mastersubstrate 100 is completed. In the case of performing the deep cuttingprocess, the processes of steps S140 to S160 are further performed.Steps S140 to S160 are the same as those described above. This processthen ends.

The cutting distance by the cutting tool 60 is not limited. For example,the cutting distance may be 100 km or less, and may be 20 km or less.Cutting can be continued until the tool cutter 62 is damaged.

The depth of the fine concave portion 110 is not limited. For example,the depth of the fine concave portion 110 may be 1 μm to 200 μm, and ispreferably 3 μm to 30 μm. The distance between the fine concave portions110 (i.e. the pitch of the fine concave portion 110) is not limited. Forexample, the pitch of the fine concave portion 110 may be 5 μm to 500μm, and is preferably 10 μm to 100 μm.

<6. Structure of Master>

FIGS. 10A, 10B, and 10C each illustrate an example of the master 120produced by the above-described microfabrication method.

The master 120 is, for example, a transfer mold used in imprinttechnology. The master 120 has a columnar or cylindrical shape, and manyfine concave portions 110 are formed on its circumferential surface. Atleast one of the sidewall 110 b and the bottom 110 a of the fine concaveportion 110 has an oscillation waveform that satisfies at least one ofthe following oscillation waveform conditions (1) to (4) (preferably allof the oscillation waveform conditions (1) to (4)).

Oscillation waveform condition (1): the oscillation waveform iscontinuous.

Oscillation waveform condition (2): the oscillation waveform is acomposite waveform of a plurality of oscillation waveforms, and theplurality of oscillation waveforms are in phase with each other.

Oscillation waveform condition (3): fine concave portions 110 of aplurality of rows are formed on the master substrate 100, and theoscillation waveforms of adjacent fine concave portions 110 are in phasewith each other.

Oscillation waveform condition (4): fine concave portions 110 of aplurality of rows are formed on the master substrate 100, and theoscillation waveforms of fine concave portions 110 are in phase witheach other for every two pitches (i.e. every two rounds).

The oscillation waveform condition (1) corresponds to the foregoingcutting condition (1). The oscillation waveform condition (1) can besatisfied if the error in cutting of the cutting condition (1) is withinthe acceptable error range. The oscillation waveform condition (2)corresponds to the deep cutting process satisfying the cutting condition(2). The oscillation waveform conditions (3) and (4) correspond to theround slice cutting pattern or the helical cutting pattern satisfyingthe cutting condition (2). The expression “in phase with each other” inthe oscillation waveform conditions (2) to (4) denotes that the phase atthe same y coordinate of the master 120 is the same, i.e. the error incutting of the cutting condition (2) is within the acceptable errorrange. In the oscillation waveform condition (4), the oscillationwaveforms of adjacent fine concave portions 110 are 180° out of phasewith each other. FIGS. 6A to 8B each illustrate an example of the shapeof the fine concave portions 110.

Since the oscillation waveform of the master 120 satisfies at least oneof the oscillation waveform conditions (1) to (4), the continuity of theoscillation waveform is maintained without a defect.

<7. Structure of Transfer Object>

FIGS. 11A and 11B illustrate an example of the transfer object 200produced by transferring the surface shape of the master 120. Thetransfer object 200 includes a transfer object substrate 210 and a fineconcave-convex layer 220 formed on the surface of the transfer objectsubstrate 210. The fine concave-convex layer 220 includes many fineconcave portions 230 and fine convex portions 240 formed between thefine concave portions 230. The surface shape of the fine concave-convexlayer 220 is an inversion of the surface shape of the master 120. Thatis, the shape of the fine concave portions 230 is an inversion of theshape of the fine convex portions 111, and the shape of the fine convexportions 240 is an inversion of the shape of the fine concave portions110. The transfer object 200 illustrated in FIGS. 11A and 11B isproduced using the master 120 illustrated in FIGS. 7A and 7B.

At least one of the sidewall 230 b and the bottom 230 a of the fineconcave portion 230 has an oscillation waveform that satisfies at leastone of the following oscillation waveform conditions (1) to (4)(preferably all of the oscillation waveform conditions (1) to (4)).

Oscillation waveform condition (1): the oscillation waveform iscontinuous.

Oscillation waveform condition (2): the oscillation waveform is acomposite waveform of a plurality of oscillation waveforms, and theplurality of oscillation waveforms are in phase with each other.

Oscillation waveform condition (3): fine concave portions 230 of aplurality of rows are formed on the transfer object substrate 210, andthe oscillation waveforms of adjacent fine concave portions 230 are inphase with each other.

Oscillation waveform condition (4): fine concave portions 230 of aplurality of rows are formed on the transfer object substrate 210, andthe oscillation waveforms of fine concave portions 230 are in phase witheach other for every two pitches.

The oscillation waveform conditions (1) to (4) correspond to theoscillation waveform conditions (1) to (4) of the master 120. Theexpression “in phase with each other” in the oscillation waveformconditions (2) to (4) of the transfer object 200 denotes that, in thecase where the extending direction of the fine concave portions 230 isthe y-axis, the phase at the same y coordinate is the same. In theoscillation waveform condition (4), the oscillation waveforms ofadjacent fine concave portions 230 are 180° out of phase with eachother.

Since the oscillation waveform of the transfer object 200 satisfies atleast one of the oscillation waveform conditions (1) to (4), thecontinuity of the oscillation waveform is maintained without a defect.

<8. Manufacturing Method for Transfer Object>

The transfer object 200 is produced by transferring the fine concaveportions 110 of the master 120. For example, an uncured curable resinlayer is formed on the transfer object substrate 210. The material ofthe transfer object substrate 210 may be selected as appropriatedepending on the use of the transfer object 200. Examples of thematerial of the transfer object substrate 210 include acrylic resin(polymethylmethacrylate, etc.), polycarbonate, PET (polyethyleneterephthalate), TAC (triacetylcellulose), polyethylene, polypropylene,cycloolefin polymer, cycloolefin copolymer, and vinyl chloride.

The curable resin material may be selected as appropriate depending onthe use of the transfer object 200. Examples of the curable resinmaterial include epoxy curable resin and acrylic curable resin.

Next, the surface of the master 120 is pressed against the curable resinlayer. The curable resin layer is cured in this state. In this way, thesurface shape of the master 120 is transferred to the curable resinlayer. That is, the fine concave-convex layer 220 is formed on thetransfer object substrate 210. The master 120 is then peeled off fromthe fine concave-convex layer 220, to produce the transfer object 200.In this embodiment, the master 120 has a columnar or cylindrical shape,so that the transfer object 200 can be continuously produced byroll-to-roll process.

This is merely an example of the manufacturing method for the transferobject 200, and the transfer object 200 may be produced by othermanufacturing methods. For example, the transfer object substrate 210may be made of thermoplastic resin. In this case, the surface of themaster 120 is pressed against the transfer object substrate 210 softenedby heating. By cooling the transfer object substrate 210 in this state,the fine concave-convex layer 220 is formed on the surface of thetransfer object substrate 210.

EXAMPLES 1. Example 1

Examples of this embodiment will be described below. In Example (Ex.) 1,the master substrate 100 of a columnar shape with a diameter of 250 mmand a length of 1000 mm was prepared. The material was S45C. The mastersubstrate 100 was then subjected to nickel-phosphorus plating to form acoating layer on the master substrate 100. The coating layer was thenflattened. The specific process for flattening is as described above.

Next, the microfabrication device 1 was prepared. As the cutting tool60, a diamond bit whose tool tip 63 has a V shape was prepared. Thenumber of rotations of the master substrate 100 was 20 min⁻¹. Theoscillation waveform of the cutting tool 60 was a sine waveform with anamplitude of 10 μm and a frequency of 300 Hz. The oscillation directionwas the z₂-axis direction. Cutting in the helical cutting pattern wasperformed so as to satisfy the foregoing cutting condition (1) and/or(2). The pitch of the fine concave portion 110 was 70 μm. Further, twosets of the deep cutting process satisfying the foregoing cuttingcondition (1) and/or (2) was performed. The difference between thecutting depth of the first set and the cutting depth of the second set(specifically, the difference between the maximum displacements of theoscillations), i.e. the cutting difference, was 3 μm.

The produced master 120 was then used to produce a transfer object. Thesurface shape of the transfer object was observed using a microscope ofa magnification of 450 times and a scanning electron microscope (SEM) ofa magnification of 100 times. As a result, the oscillation waveform wascontinuously formed in the fine concave portions 110, and no defect wasfound.

2. Example 2

The same test as in Example 1 was performed, except that the cuttingpattern was the round slice cutting pattern. The pitch of the roundslice cutting pattern was the same as in Example 1. As a result, theoscillation waveform was continuously formed in the fine concaveportions 110, and no defect was found.

3. Example 3

The same test as in Example 1 was performed, except that the cuttingpattern was the cross helical cutting pattern. The pitch of the crosshelical cutting pattern was the same as in Example 1. As a result, theoscillation waveform was continuously formed in the fine concaveportions 110, and no defect was found.

4. Comparative Example 1

In Comparative Example (Comp. Ex.) 1, the same process as in Example 1was performed, except that the deep cutting process of the first set andthe deep cutting process of the second set were 45° out of phase witheach other and the cutting difference was 0. That is, in ComparativeExample 1, cutting not satisfying the cutting condition (2) wasperformed. FIG. 12 illustrates the oscillation waveform. In FIG. 12 ,the horizontal axis represents the oscillation phase)(°, and thevertical axis represents the oscillation displacement (z₂ coordinatevalue+cutting difference). A graph L11 represents the oscillationwaveform of the deep cutting process of the first set, and a graph L12represents the oscillation waveform of the deep cutting process of thesecond set. The maximum difference (hereafter also referred to as “depthvariation amount”) D between the graphs L11 and L12 was about 25% of thedepth set value (amplitude+cutting difference). A graph L13 in FIG. 13represents the oscillation waveform of the fine concave portions 110.The horizontal axis represents the oscillation phase)(° of the fineconcave portions 110, and the vertical axis represents the amplitude ofthe fine concave portions 110. In Examples 1 to 3, the graphs L11 andL12 are in phase with each other.

The surface shape of the transfer object produced in Comparative Example1 was observed using a microscope of a magnification of 450 times and ascanning electron microscope (SEM) of a magnification of 100 times. As aresult, a defect was found in the fine concave portions 110. FIG. 21illustrates a microscope image as an example of an observed image. Ascan be seen from FIG. 21 , a defect A was found in part of the fineconcave portions 110.

5. Comparative Example 2

In Comparative Example 2, the same process as in Comparative Example 1was performed, except that the phase difference between the deep cuttingprocess of the first set and the deep cutting process of the second setwas 90°. In Comparative Example 2, the depth variation amount D was 50%of the depth set value. The defect was found in Comparative Example 2,too.

6. Comparative Example 3

In Comparative Example 3, the same process as in Comparative Example 1was performed, except that the phase difference between the deep cuttingprocess of the first set and the deep cutting process of the second setwas 180°. In Comparative Example 3, the depth variation amount D was100% of the depth set value. The defect was found in Comparative Example3, too.

7. Comparative Example 4

In Comparative Example 4, the same process as in Comparative Example 1was performed, except that the phase difference between the deep cuttingprocess of the first set and the deep cutting process of the second setwas 10°. In Comparative Example 4, the depth variation amount D was 5%of the depth set value. The defect was found in Comparative Example 4,too.

8. Comparative Example 5

In Comparative Example 5, the same process as in Comparative Example 1was performed, except that the phase difference between the deep cuttingprocess of the first set and the deep cutting process of the second setwas 5°. In Comparative Example 5, the depth variation amount D was 3% ofthe depth set value. The defect was found in Comparative Example 5, too.

9. Comparative Example 6

In Comparative Example 6, the same process as in Comparative Example 1was performed, except that the cutting difference was 3 μm. FIG. 14illustrates the oscillation waveform. In FIG. 14 , the horizontal axisrepresents the oscillation phase)(°, and the vertical axis representsthe oscillation displacement (z₂ coordinate value+cutting difference). Agraph L11 represents the oscillation waveform of the deep cuttingprocess of the first set, and a graph L12 represents the oscillationwaveform of the deep cutting process of the second set. The depthvariation amount D was about 25% of the depth set value. A graph L13 inFIG. 15 represents the oscillation waveform of the fine concave portions110. The horizontal axis represents the oscillation phase)(° of the fineconcave portions 110, and the vertical axis represents the amplitude ofthe fine concave portions 110. The defect was found in ComparativeExample 6, too.

10. Comparative Example 7

In Comparative Example 7, the same process as in Comparative Example 2was performed, except that the cutting difference was 3 μm. The depthvariation amount D was about 50% of the depth set value. The defect wasfound in Comparative Example 7, too.

11. Comparative Example 8

In Comparative Example 8, the same process as in Comparative Example 3was performed, except that the cutting difference was 3 μm. The depthvariation amount D was about 100% of the depth set value. The defect wasfound in Comparative Example 8, too. FIG. 22 illustrates an SEM image asan example of an observed image. As can be seen from the SEM image, thedefect A was found in Comparative Example 8.

12. Comparative Example 9

In Comparative Example 9, the same process as in Example 1 wasperformed, except that the cutting difference was 3 μm and the phasedifference was 40°. The depth variation amount D was about 22% of thedepth set value. The defect was found in Comparative Example 9, too.

13. Comparative Example 10

In Comparative Example 10, the same process as in Example 1 wasperformed, except that the cutting difference was 3 μm and the phasedifference was 50°. The depth variation amount D was about 27% of thedepth set value. The defect was found in Comparative Example 10, too.

14. Comparative Example 11

In Comparative Example 11, the same process as in Comparative Example 2was performed, except that the amplitude was 3 μm and the cuttingdifference was 1.5 μm. FIG. 16 illustrates the oscillation waveform. InFIG. 16 , the horizontal axis represents the oscillation phase °), andthe vertical axis represents the oscillation displacement (z₂ coordinatevalue+cutting difference). A graph L11 represents the oscillationwaveform of the deep cutting process of the first set, and a graph L12represents the oscillation waveform of the deep cutting process of thesecond set. The depth variation amount D was about 50% of the depth setvalue. A graph L13 in FIG. 17 represents the oscillation waveform of thefine concave portions 110. The horizontal axis represents theoscillation phase)(° of the fine concave portions 110, and the verticalaxis represents the amplitude of the fine concave portions 110. Thedefect was found in Comparative Example 11, too.

15. Comparative Example 12

In Comparative Example 12, the same process as in Comparative Example 3was performed, except that the amplitude was 3 μm and the cuttingdifference was 1.5 μm. The depth variation amount D was about 100% ofthe depth set value. The defect was found in Comparative Example 12,too.

16. Comparative Example 13

In Comparative Example 13, the same process as in Comparative Example 1was performed, except that the cutting pattern was the round slicecutting pattern. The defect was found in Comparative Example 13, too.

17. Comparative Example 14

In Comparative Example 14, the same process as in Comparative Example 2was performed, except that the cutting pattern was the round slicecutting pattern. The defect was found in Comparative Example 14, too.

18. Comparative Example 15

In Comparative Example 15, the same process as in Comparative Example 3was performed, except that the cutting pattern was the round slicecutting pattern. The defect was found in Comparative Example 15, too.

19. Comparative Example 16

In Comparative Example 16, the cutting pattern was the round slicecutting pattern. Further, cutting not satisfying the cutting condition(1) was performed, without the deep cutting process. Specifically,cutting was performed so that the length of the overlap was 110 μm andthe difference in level was 0.6 μm in the foregoing case 1. FIG. 18illustrates the oscillation waveform of the cutting. In FIG. 18 , thehorizontal axis represents the y coordinate value)(°, and the verticalaxis represents the oscillation displacement (μm). A graph L4 representsthe oscillation waveform near the start point, and a graph L5 representsthe oscillation waveform near the end point. A distance D2 representsthe depth of the difference in level, and a distance D3 represents thelength of the overlap. In Comparative Example 16, the defect was foundat the boundary part between the start point and the end point.

20. Example 4

The same process as in Comparative Example 16 was performed, except thatthe length of the overlap was 6.2 μm and the difference in level was0.003 μm. As a result, no defect was found.

21. Comparative Example 17

In Comparative Example 17, the cutting pattern was the round slicecutting pattern. Further, cutting not satisfying the cutting condition(1) was performed, without the deep cutting process. Specifically,cutting was performed so that the length of the flat part was 0.55 μm inthe foregoing case 2. FIG. 19 illustrates the oscillation waveform ofthe cutting. In FIG. 19 , the horizontal axis represents the ycoordinate value)(°, and the vertical axis represents the oscillationdisplacement (μm). A graph L6 represents the oscillation waveform nearthe start point, and a graph L7 represents the oscillation waveform nearthe end point. A distance D4 represents the length of the flat part (thelength in the y-axis direction). In Comparative Example 17, the defectwas found at the boundary part between the start point and the endpoint.

22. Example 5

The same process as in Comparative Example 17 was performed, except thatthe length of the flat part was 0.2 μm. As a result, no defect wasfound.

23. Example 6

The same test as in Example 1 was performed, except that the cuttingpattern was the thrust cutting pattern. In Example 6, the cutting tool60 was oscillated synchronously with the coordinate of the feed shaft31. The output x₂z₂ coordinate value of the cutting tool 60 wasgenerated using an arbitrary waveform generator. Processing was startedwithout rotating the master substrate 100, and, upon detecting the firsttrigger of the encoder of the feed shaft 31, an arbitrary waveform wasgenerated to drive the tool mounting portion 40. As a result, theoscillation waveform was continuously formed in the fine concaveportions 110, and no defect was found.

24. Example 7

The same test as in Example 6 was performed, except that the cuttingpattern was the oblique thrust cutting pattern. In the oblique thrustcutting pattern in Example 7, the inclination angle of the fine concaveportions 110 with respect to the axis direction of the master substrate100 was 15°. As a result, the oscillation waveform was continuouslyformed in the fine concave portions 110, and no defect was found.

These results are listed in Tables 1 and 2.

TABLE 1 Ex. Ex. Ex. Ex. Ex. Ex. Ex. 1 2 3 4 5 6 7 Cutting Helical Roundslice Cross helical Round slice Round slice Thrust Oblique thrustpattern Synchronous Performed Performed Performed Performed PerformedPerformed Performed control Cutting 3 3 3 — — 3 3 difference (μm) Phase0 0 0 — — 0 0 difference (°) Length of — — — 0.003 0.2 — — difference inlevel or flat part (μm) Defect Not found Not found Not found Not foundNot found Not found Not found

TABLE 2 Comp. Ex. Comp. Ex. Comp. Ex. Comp. Ex. Comp. Ex. Comp. Ex. 1 to5 6 to 10 11 to 12 13 to 15 16 17 Cutting Helical Helical Helical Roundslice Round slice Round slice pattern Synchronous Not performed Notperformed Not performed Not performed Not performed Not performedcontrol Cutting 0 3 1.5 0 — — difference (μm) Phase 5 to 180 5 to 180 90to 180 45 to 180 — — difference (°) Length of — — — — 0.6 0.55difference in level or flat part (μm) Defect Found Found Found FoundFound Found

In Examples satisfying the cutting condition (1) and/or (2), no defectwas found. In Comparative Examples 1 to 17 not satisfying the cuttingconditions (1) and (2), the defect was found.

While disclosed embodiments have been described in detail above withreference to the attached drawings, the present disclosure is notlimited to such embodiments. It is clear that, within the scope of thetechnical idea defined in the claims, various changes or modificationsare conceivable by a person with ordinary skill in the technical fieldto which the presently disclosed techniques belong, and these changes ormodifications are also included in the technical scope of the presentdisclosure. For example, although the oscillation waveform of thecutting tool 60 is a sine waveform in the foregoing embodiments, theoscillation waveform of the cutting tool 60 is not limited to such, andmay be any oscillation waveform. The oscillation waveform may be atrapezoidal waveform or the like.

For example, although the master substrate 100 has a columnar orcylindrical shape in the foregoing embodiments, the master substrate 100is not limited to such, and may have a platelike shape as an example. Inthis case, for example, the y-axis is the length direction of the fineconcave portions. Although the cutting target is a master substrate inthe foregoing embodiments, the presently disclosed techniques may beused for cutting of other substrates.

REFERENCE SIGNS LIST

-   -   1 microfabrication device    -   10 main rotation device    -   12 follower rotation device    -   20 cutting device    -   30 processing stage    -   31 feed shaft    -   40 tool mounting portion    -   41 case storage recess    -   50 oscillator    -   51 tool storage case    -   52 a, 53 a tool oscillation element    -   52 b, 53 b displacement measuring instrument    -   60 cutting tool    -   61 tool body    -   62 tool cutter    -   63 tool tip    -   70 control device    -   71 control calculator    -   72 controller    -   73 amplifier    -   100 master substrate    -   110 fine concave portion    -   110 a bottom    -   110 b sidewall    -   111 fine convex portion    -   120 master    -   200 transfer object    -   210 transfer object substrate    -   220 fine concave-convex layer    -   230 fine concave portion    -   230 a bottom    -   230 b sidewall    -   240 fine convex portion

1. A transfer object comprising a substrate having one or more fineconcave portions formed on a surface thereof, wherein at least one of asidewall and a bottom of each fine concave portion has an oscillationwaveform satisfying at least one of: an oscillation waveform condition(1) that the oscillation waveform is continuous; an oscillation waveformcondition (2) that the oscillation waveform is a composite waveform of aplurality of oscillation waveforms, and the plurality of oscillationwaveforms are in phase with each other; an oscillation waveformcondition (3) that fine concave portions of a plurality of rows areformed on the substrate, and oscillation waveforms of adjacent fineconcave portions are in phase with each other; and an oscillationwaveform condition (4) that fine concave portions of a plurality of rowsare formed on the substrate, and oscillation waveforms of the fineconcave portions are in phase with each other for every two pitches.